[Pw_forum] How can I define a Supercell in my simulation?

[lan haiping]

Hi,
QE package performs calculation with periodic cell.
if you want to do non-periodic calculations , you should
set up supercell with  large vacuum seperations between
the periodic images.

With respect to  carbon nanotubes,
you can define ibrav to 6 with certain values for celldm(1) and celldm(3),
such as celldm(1)=47.243171944358878, celldm(3) =0.1704 for zigzag
nanotube.  If you want to simulate finite  carbon nanotubes,  what you need
is to define some value along longitudinal direction.

Regards,

On Fri, Dec 12, 2008 at 3:50 PM, Reza Kalantari <
rezakalantarinezhad at gmail.com> wrote:

> Dear Paolo Giannozzi
>
> Thank you so much for your attention. I have seen Marzari's group
> simulations on carbon nanotube which were done with Quantum-Espresso but all
> examples of Quantum-Espresso on its official website are for periodic mater
> so I don't have a sample input file for a non-periodic simulation.
> Where can I find an input sample file (pw.x input file) for a non-periodic
> simulation?
> How should I define ibrav | celldm | assume_isolated?
> Should I define CELL_PARAMETERS ?
> I try to calculate electronic structure of a carbon nanotube when another
> biomolecule dock with it. have seen ever such as this by Quantum-Espresso? I
> want to know that it's a conceptual barrier to this purpose  with
> Quantum-Espresso?
> Thank you very much again for you attention. I have started working on this
> subject recently so maybe my questions are rudimentary so sorry.
>
> Reza Kalantari-Nezhad
> PhD Student
> Amir Kabir University of Technology
> rezakalantarinezhad at gmail.com
> rkalantari at aut.ac.ir
>
>
> On Thu, Dec 11, 2008 at 4:34 PM, Paolo Giannozzi <giannozz at democritos.it>wrote:
>
>> On Dec 11, 2008, at 7:29 , Reza Kalantari wrote:
>> > I know that I should use supercell for this purpose but I don't
>> > know how can I do it?
>> >
>> there is no conceptual difference between a so-called "supercell" and
>> a crystal cell.
>> > Have you seen ever such as this simulation by Quantum-Espresso?
>> >
>> like this? http://web.mit.edu/newsoffice/2006/nanotubes.html
>>
>> P.
>> ---
>> Paolo Giannozzi, Democritos and University of Udine, Italy
>>
>>
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>
>
>
> --
> Eradatmand
> Reza Kalantari Nezhad
> PhD Student
> Mechanical Engineering
> Amir Kabir University of Technology (Tehran Polytechnic)
> Tehran
> Iran
>
>
> Mobile Phone: 0098-935-2578543
>
>
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>


-- 
Hai-Ping Lan
Department of Electronics ,
Peking University , Bejing, 100871
lanhaiping at gmail.com, hplan at pku.edu.cn
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